International Space Station

Source: NASA


The International Space Station (ISS), a convergence of science, technology, and human innovation, is a modular space station in low Earth orbit. It serves as a world-class laboratory in space, offering research conditions not possible on Earth.[1] The ISS provides:

  • Crew habitat
  • Ports for docking and berthing of visiting vehicles
  • A microgravity and life sciences laboratory
  • A test bed for new technologies
  • A platform for Earth and celestial observations [2]

Now the unique environment of space and the full capabilities of the ISS are available for innovative commercial use, including academic and government research. ISS can accommodate research in the areas of:

  • Earth and Space Science
  • Biology and Biotechnology
  • Human Research
  • Physical Science
  • Technology Demonstrations
  • Educational Activities [3]


Launched in 1998 and involving the U.S., Russia, Canada, Japan, and the participating countries of the European Space Agency, ISS is one of the most ambitious international collaborations ever attempted.[4] Partner organizations include:

  • United States – NASA
  • Russia – State Space Corporation ROSCOSMOS (ROSCOSMOS)
  • Canada – Canadian Space Agency (CSA)
  • Japan – Japan Aerospace Exploration Agency (JAXA)
  • Europe – European Space Agency (ESA), which includes the following member countries:
  1. Belgium
  2. Denmark
  3. France
  4. Germany
  5. Italy
  6. Netherlands
  7. Norway
  8. Spain
  9. Sweden
  10. Switzerland
  11. United Kingdom [5]

Continuously occupied since November 2000, the ISS maintains an international crew of six people who live and work while traveling at a speed of five miles per second, orbiting Earth every 90 minutes. [6]

263 individuals from 20 countries have visited the International Space Station. There have been 254 spacewalks at the ISS since 1998.


  • Pressurized Module Length: 239.4 feet (73 meters)
  • Truss Length: 357.5 feet (109 meters)
  • Solar Array Length: 115 feet (35 meters)
  • Mass: 925,335 pounds (419,725 kilograms)
  • Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles
  • Pressurized Volume: 32,333 cubic feet (916 cubic meters)
  • With BEAM expanded: 32,898 cubic feet (932 cubic meters)
  • Power Generation: 8 solar arrays provide 75 to 90 kilowatts of power
  • Lines of Computer Code: approximately 1.5 million
  • Space Station Speed: 17,500 mph (28,000 km/h) [7]


In addition to facilitating the growth of a robust commercial market in low-Earth orbit; operating as a national laboratory for scientific research; and facilitating the development of U.S. commercial cargo and commercial crew space transportation capabilities, the ISS also serves as a springboard to NASA’s next great leap in exploration, enabling research and technology developments that will benefit human and robotic exploration of destinations beyond low-Earth orbit, including asteroids and Mars. [8]


  • Microgravity, or weightlessness, alters many observable phenomena within the physical and life sciences. Systems and processes affected by microgravity include surface wetting and interfacial tension, multiphase flow and heat transfer, multiphase system dynamics, solidification, and fire phenomena and combustion. Microgravity induces a vast array of changes in organisms ranging from bacteria to humans, including global alterations in gene expression and 3-D aggregation of cells into tissue-like architecture. [9]
  • Extreme conditions in the ISS space environment include exposure to extreme heat and cold cycling, ultra-vacuum, atomic oxygen, and high energy radiation. Testing and qualification of materials exposed to these extreme conditions have provided data to enable the manufacturing of long-life reliable components used on Earth as well as in the world’s most sophisticated satellite and spacecraft components. [10]
  • Low-Earth orbit at an orbital inclination of 51.6 degrees, each orbit takes 90-93 minutes, depending on the exact altitude of the ISS, and affords a unique vantage point of the Earth. With an altitude of approximately 220 miles (350 kilometers) above Earth, the ISS orbits at an average speed of 17,227 miles (27,724 km) per hour, orbiting around Earth approximately 16 times per day. This can provide improved spatial resolution and variable lighting conditions compared to the sun-synchronous orbits of typical Earth remote-sensing satellites. [11]


Several research facilities are in place aboard the ISS to support microgravity science investigations, including those in biology, biotechnology, human physiology, material science, physical sciences, and technology development. [12]

  • Standard Payload Racks: Research payloads within the U.S., European, and Japanese ISS laboratories typically are housed in a standard rack, such as the International Standard Payload Rack (ISPR). Smaller payloads may fit in ISS lockers carried in a rack framework. [13]
  • Active Rack Isolation System (ARIS): The ARIS is designed to isolate payload racks from vibration. The ARIS is an active electromechanical damping system attached to a standard rack that senses the vibratory environment with accelerometers and then damps it by introducing a compensating force. [14]


External Earth and Space Science hardware platforms are located at various places along the outside of the ISS. Locations include:

  • Columbus External Payload Facility (CEPF)
  • Russian Service Module
  • Japanese Experiment Module Exposed Facility (JEM-EF)
  • Four EXPRESS Logistics Carriers (ELC)
  • Alpha Magnetic Spectrometer (AMS)
  • Nauka Multipurpose Laboratory Module (MLM)
  • Rassvet Mini-Research Module-1 [15]

External facility investigations include those related to astronomy; Earth observation; and exposure to vacuum, radiation, extreme temperature, and orbital debris. [16]

External Payload Accommodations: External payloads may be accommodated at several locations on the U.S. S3 and P3 Truss segments. External payloads are accommodated on an Expedite the Processing of Experiments to the Space Station racks (EXPRESS) Logistics Carrier (ELC). Mounting spaces are provided, and interfaces for power and data are standardized to provide quick and straightforward payload integration. Payloads can be mounted using the Special Purpose Dexterous Manipulator (SPDM), Dextre, on the ISS’s robotic arm. [17]


The presence of humans onboard ISS has provided a foundation for numerous educational activities aimed at capturing that interest and motivating study in the sciences, technology, engineering and mathematics (STEM). Over 43 million students from 64 countries around the world have participated in ISS-related educational activities. Having the opportunity to connect with crewmembers real-time, either through” live” downlinks or simply speaking via a ham radio, ignites the imagination of students about space exploration and its application to the STEM fields. Projects such as Earth Knowledge-based Acquired by Middle Schools (EarthKAM) have allowed for global student, teacher and public access to space through student image acquisition. This serves to support inquiry-based learning which is an approach to science education that allows students to ask questions, develop hypothesis-derived experiments, obtain supporting evidence, analyze data, and identify solutions or explanations. Through expanded international cooperation, the next generation of scientists, engineers and explorers from our global community will have the capability to learn more about and be involved in space exploration. [18]


NASA maintains an online resource of ISS Publications, containing the results from research and experiments onboard the Space Station, as well as on Shuttle Missions to the ISS, available here.


As the third brightest object in the night sky, the ISS is visible to the naked eye. Viewers can access a new interactive map to find sighting opportunities, or sign up to get email or text alerts when the space station is flying over, by visiting here.

CLDs to Replace ISS by 2030

The LEO-based (Low Earth Orbit) International Space Station (ISS) is scheduled to end operations in 2030. Between now and then, private companies will increasingly work with governments to privatize more and more space activities and structures – as part of what is becoming known as the Low Earth Orbit Economy. [1]

Under its Commercial LEO Development Program, NASA plans to transition the work now being done at the International Space Station to several commercial space stations. To begin that process, NASA has selected four companies to design and develop what it calls Commercial LEO Destinations, or CLDs. The goal is for several CLDs to begin operations in the late 2020s. These CLDs will provide a variety of services to both government and private sector customers. The four Phase 1 selected companies – Axiom, Nanoracks, Northrop Grumman, and Blue Origin - will each develop their own CLD. The types of services offered will include opportunities for NASA to continue the type of research now done on ISS, as well as services that will be needed by an emerging commercial LEO community. In Phase 2, NASA intends to put out a firm fixed-price services contract that spells out the types of services NASA wants to be able to purchase from some of the CLD space stations. [1] [2]

Updated November 2022 by Kristin Stiner and Tina Allen